<template>
  <div class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>考试时间</th>
            <th>操作</th>
          </tr>
        </thead>
        <tbody v-if="list.length">
          <tr v-for="item in list" :key="item.id">
            <td>{{ item.id }}</td>
            <td>{{ item.subject }}</td>
            <td :class="{ red: item.score <= 60 }">{{ item.score }}</td>
            <td>{{ formatData(item.data) }}</td>
            <td><a href="#" @click.prevent="dalet(item.id)">删除</a></td>
          </tr>
        </tbody>
        <tbody v-else>
          <tr>
            <td colspan="5">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody>
        <tfoot>
          <tr>
            <td colspan="5">
              <span>总分：{{ sum }}</span>
              <span style="margin-left: 50px" v-if="this.list.length !== 0"
                >平均分：{{ (sum / list.length).toFixed(2) }}</span
              >
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <input type="text" placeholder="请输入科目" v-model.trim="subject" />
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <input
            type="text"
            placeholder="请输入分数"
            v-model.number.trim="score"
          />
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <button class="submit" @click="add">添加</button>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
// 导入moment
import moment from 'moment'

export default {
  name: 'ScoreCase',
  data() {
    return {
      // 打开页面取出本地存储的数据字符串并改成数组
      // 如果为空的话给入默认值
      list:JSON.parse(localStorage.getItem('subjectlist')) || [
        {
          id: 1,
          subject: '语文',
          score: 89,
          date: new Date('2022/06/07 10:00:00'),
        },
        {
          id: 2,
          subject: '数学',
          score: 100,
          date: new Date('2022/06/07 15:00:00'),
        },
        {
          id: 3,
          subject: '英语',
          score: 56,
          date: new Date('2022/06/08 10:00:00'),
        },
        {
          id: 4,
          subject: '物理',
          score: 76,
          date: new Date('2022/06/08 10:00:00'),
        },
      ],
      subject: '',
      score: '',
    }
  },

  methods: {
    // 添加事件
    add() {
      // 如果添加的内容为空则弹提示框
      if(this.subject === '' || this.score === '') return alert('输入的数据不能为空'),
      this.list = [
        ...this.list,
        {
          id: this.list.length + 1,
          subject: this.subject,
          score: this.score,
          date: new Date(),
        },
      ]

    // 清空输入框
      this.subject = '', 
      this.score = ''
    },

    // 删除事件
    dalet(id) {
      this.list = this.list.filter((item) => item.id !== id)
    },

    // 当前时间
    formatData(data) {
      return moment(data).format(' YYYY-MM-DD HH:mm:ss')
    },
  },

  computed: {
    sum() {
      return this.list.reduce((prev, item) => {
        return prev + item.score
      }, 0)
    },
  },
  
  // 深度监听list 
  watch: {
    deep: true,
    list(newval) {
      // 把新变化的数据存入本地，并把数据改成字符串
      localStorage.setItem('subjectlist', JSON.stringify(newval))
    },
  },
}
</script>

<style lang="less">
.score-case {
  width: 1000px;
  margin: 50px auto;
  display: flex;
  .table {
    flex: 4;
    table {
      width: 100%;
      border-spacing: 0;
      border-top: 1px solid #ccc;
      border-left: 1px solid #ccc;
      th {
        background: #f5f5f5;
      }
      tr:hover td {
        background: #f5f5f5;
      }
      td,
      th {
        border-bottom: 1px solid #ccc;
        border-right: 1px solid #ccc;
        text-align: center;
        padding: 10px;
        &.red {
          color: red;
        }
      }
    }
    .none {
      height: 100px;
      line-height: 100px;
      color: #999;
    }
  }
  .form {
    flex: 1;
    padding: 20px;
    .form-item {
      display: flex;
      margin-bottom: 20px;
      align-items: center;
    }
    .form-item .label {
      width: 60px;
      text-align: right;
      font-size: 14px;
    }
    .form-item .input {
      flex: 1;
    }
    .form-item input,
    .form-item select {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      width: 200px;
      height: 40px;
      box-sizing: border-box;
      padding: 10px;
      color: #666;
    }
    .form-item input::placeholder {
      color: #666;
    }
    .form-item .cancel,
    .form-item .submit {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      border-radius: 4px;
      padding: 4px 10px;
      margin-right: 10px;
      font-size: 12px;
      background: #ccc;
    }
    .form-item .submit {
      border-color: #069;
      background: #069;
      color: #fff;
    }
  }
}
</style>
